Reference frequency generation and acceleration sensing are typically implemented by two separate discrete components in devices which require both. A quartz crystal resonator is most often used to generate the reference frequency, while acceleration sensing is often measured by using electrostatic, piezoelectric or piezoresistive principles. Many applications also use shock sensing, which provides for the detection of rapid acceleration changes and can be described as a wide-band acceleration sensor.
Using separate components for frequency generation and sensing, however, takes up more space and also can require more power. These are significant disadvantages, particularly in applications in which a small size as well as low power consumption are desired or required, such as in wheel-mounted tire pressure monitoring systems (TPMS).